Robin Schmittel explains a filter that eliminates solid inorganic waste. The inorganic material is transported to the landfill.

After two years of operating the wastewater treatment plant, public works staff is still trying to perfect the new green technology.

The multistage aerated biological process treatment plant near the corner of Riverside Avenue and Monte Street has become known for an unpleasant odor that wafts through the neighborhood. On a recent tour of the facility, town board members learned about filtration process and possible sources of the smell.

The system uses bacteria to eat organic human waste. But when exposure to inorganic chemicals can kill off bacteria and when there is not enough bacteria, the system doesn't function as efficiently as it could, said Public Works Director Robin Schmittel.

"We're so used to flushing everything, we're killing our own supergreen plant," said Trustee Will Stone, who summed up a potential problem at the end of the tour.

Another potential odor-causing problem could be lack of food, said Schmittel. The plant processes about 85,000 gallons of water a day.

The plant was installed because it was two-thirds the price of the alternative system the state suggested. It was also projected to purify water better than a traditional system. The water currently released back into the river is much cleaner than the state requires, said Schmittel.

Chemicals are also challenge for the plant. Products like antifreeze work through the system in about 20 hours instead of 28 days, which was the timeline for the lagoons used primarily purify water previously. But the bacteria in the plant take hours grow back after chemicals come through and that is when the plant could get smelly.

The state is requiring the town to continue to operate the lagoons as a back up to the plant. Backwash from one of the plant's filters feeds into the lagoons currently. In time, the plant is meant to replace the aerated lagoons completely.

Another potential source of odor is the ventilation system from the building where inorganic solids are filtered out. However, Schmittel said there are already air filters in place.

The inorganic solids that must be filtered out include toothpicks, diapers, and all kinds of plastics that are shredded by a grinder.

"Most people don't know the difference between disposable and flushable," said Schmittel.

Schmittel hauls a half a ton of inorganic waste to the landfill each week.

Robin Schmittel explains the grinder that shreds all the solids entering the wastewater treatment plant. Town trustees toured the plant on Saturday and gained a better understanding of the possible sources of the foul smells coming from the plant.